Wilkinson power dividers (also referred to as Wilkinson power splitters) are used extensively in phased array radar applications, and also in other RF applications, to split power from one line to two lines (or, alternatively, the combine power from two lines to one line). Typically, a millimeter wave (MMW) Wilkinson power divider (WPD) is implemented in a horizontal manner in the metal layers in the back-end-of-line (BEOL) processing of integrated circuit chips. As a result of their horizontally extending structure, WPDs take up a lot of space on the chip (e.g., have a large footprint).
More specifically, a WPD commonly includes an input wire that splits into two legs, a respective output at the end of each leg opposite the split, and a resistor connected between the two outputs. By definition, the legs of a WPD are of a specified length (e.g., one-quarter wavelength, i.e., λ/4) and the resistor is of a specified resistance (e.g., 2Zo), which results in the input and the two outputs all having a matched characteristic impedance (Zo). Moreover, the resistor isolates the two outputs from one another. In this way, a WPD improves over simple “Tee” and “Y” junctions by providing matching impedance at the input and output ports, and by providing isolation between the two output ports.
However, since the legs of a WPD must be of a particular length, there is a lower limit to the minimum footprint (e.g., the area when viewed in plan view) that can be achieved for adequate divider performance at a given frequency in a conventional metal-dielectric BEOL stack-up. That is to say, a large amount of chip space is required for a WPD when the legs of a WPD are implemented as horizontal traces in wiring levels above the wafer. As such, the necessary minimum size footprint of a conventionally oriented WPD negatively affects the overall cost of a phased array system.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.